Solid-state battery

ABSTRACT

A solid-state battery comprising a cathode, an anode and a solid electrolyte is provided. In one embodiment, the cathode, anode and/or solid electrolyte is formed from a printable lithium composition including lithium metal powder, a polymer binder compatible with the lithium metal powder, a rheology modifier compatible with the lithium metal powder, and a solvent compatible with the lithium metal powder and with the polymer binder. In another embodiment, lithium is deposited onto the solid electrolyte with a lithium printable lithium composition including lithium metal powder, a polymer binder compatible with the lithium metal powder, a rheology modifier compatible with the lithium metal powder, and a solvent compatible with the lithium metal powder and with the polymer binder.

RELATED APPLICATION

The following application claims priority to U.S. Provisional No.62/646,521 filed Mar. 22, 2018, and U.S. Provisional No. 62/691,819filed Jun. 29, 2018, the disclosures of which are incorporated byreference in their entireties.

FIELD OF THE INVENTION

The present invention relates to a solid-state battery which includes aprintable lithium composition.

BACKGROUND OF THE INVENTION

Lithium and lithium-ion secondary or rechargeable batteries have founduse in certain applications such as in cellular phones, camcorders, andlaptop computers, and even more recently, in larger power applicationsuch as in electric vehicles and hybrid electric vehicles. It ispreferred in these applications that the secondary batteries have thehighest specific capacity possible but still provide safe operatingconditions and good cyclability so that the high specific capacity ismaintained in subsequent recharging and discharging cycles.

Although there are various constructions for secondary batteries, eachconstruction includes a positive electrode (or cathode), a negativeelectrode (or anode), a separator that separates the cathode and anode,an electrolyte in electrochemical communication with the cathode andanode. For secondary lithium batteries, lithium ions are transferredfrom the anode to the cathode through the electrolyte when the secondarybattery is being discharged, i.e., used for its specific application.During the discharge process, electrons are collected from the anode andpass to the cathode through an external circuit. When the secondarybattery is being charged, or recharged, the lithium ions are transferredfrom the cathode to the anode through the electrolyte.

Historically, secondary lithium batteries were produced usingnon-lithiated compounds having high specific capacities such as TiS₂,MoS₂, MnO2, and V₂O₅, as the cathode active materials. These cathodeactive materials were coupled with a lithium metal anode. When thesecondary battery was discharged, lithium ions were transferred from thelithium metal anode to the cathode through the electrolyte.Unfortunately, upon cycling, the lithium metal developed dendrites thatultimately caused unsafe conditions in the battery. As a result, theproduction of these types of secondary batteries was stopped in theearly 1990s in favor of lithium-ion batteries.

Lithium-ion batteries typically use lithium metal oxides such as LiCoO₂and LiNiO₂ as cathode active materials coupled with an active anodematerial such as a carbon-based material. It is recognized that thereare other anode types based on silicon oxide, silicon particles and thelike. In batteries utilizing carbon-based anode systems, the lithiumdendrite formation on the anode is substantially avoided, thereby makingthe battery safer. However, the lithium, the amount of which determinesthe battery capacity, is totally supplied from the cathode. This limitsthe choice of cathode active materials because the active materials mustcontain removable lithium. Also, delithiated products corresponding toLi_(x)CoO₂, Li_(x)NiO₂ formed during charging and overcharging are notstable. In particular, these delithiated products tend to react with theelectrolyte and generate heat, which raises safety concerns.

New lithium-ion cells or batteries are initially in a discharged state.During the first charge of lithium-ion cell, lithium moves from thecathode material to the anode active material. The lithium moving fromthe cathode to the anode reacts with an electrolyte material at thesurface of the graphite anode, causing the formation of a passivationfilm on the anode. The passivation film formed on the graphite anode isa solid electrolyte interface (SEI). Upon subsequent discharge, thelithium consumed by the formation of the SEI is not returned to thecathode. This results in a lithium-ion cell having a smaller capacitycompared to the initial charge capacity because some of the lithium hasbeen consumed by the formation of the SEI. The partial consumption ofthe available lithium on the first cycle reduces the capacity of thelithium-ion cell. This phenomenon is called irreversible capacity and isknown to consume about 10% to more than 20% of the capacity of a lithiumion cell. Thus, after the initial charge of a lithium-ion cell, thelithium-ion cell loses about 10% to more than 20% of its capacity.

One solution has been to use stabilized lithium metal powder topre-lithiate the anode. For example, lithium powder can be stabilized bypassivating the metal powder surface with carbon dioxide such asdescribed in U.S. Pat. Nos. 5,567,474, 5,776,369, and 5,976,403, thedisclosures of which are incorporated herein in their entireties byreference. The CO₂-passivated lithium metal powder can be used only inair with low moisture levels for a limited period of time before thelithium metal content decays because of the reaction of the lithiummetal and air. Another solution is to apply a coating such as fluorine,wax, phosphorus or a polymer to the lithium metal powder such asdescribed in U.S. Pat. Nos. 7,588,623, 8,021,496, 8,377,236 and U.S.Patent Publication No. 2017/0149052, for example.

There, however, remains a need for a solid-state battery havinglithiated or prelithiated components for increased energy density andimproved safety and manufacturability.

SUMMARY OF THE INVENTION

To this end, the present invention provides a solid-state battery withone or more components prelithiated, or lithiated with a printablelithium composition. A solid-state battery comprising the printablelithium composition will have increased energy density and improvedsafety and manufacturability.

The printable lithium composition of the present invention comprises alithium metal powder, a polymer binder, wherein the polymer binder iscompatible with the lithium powder, and a rheology modifier compatiblewith the lithium powder and the polymer binder. A solvent may beincluded in the printable lithium composition, wherein the solvent iscompatible with the lithium powder and compatible with (e.g., able toform suspension or to dissolve in) the polymer binder. The solvent maybe included as a component during the initial preparation of theprintable lithium composition or added later after the printable lithiumcomposition is prepared.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of a solid-state battery according to oneembodiment of the present invention;

FIG. 2 is a temperature and pressure profile for the reactivity testingof SLMP/styrene butadiene/toluene printable lithium composition; and

FIG. 3 is a plot showing the cycle performance for a pouch cell withprintable lithium derived thin lithium film as the anode vs. commercialthin lithium foil.

DETAILED DESCRIPTION OF THE INVENTION

The foregoing and other aspects of the present invention will now bedescribed in more detail with respect to the description andmethodologies provided herein. It should be appreciated that theinvention can be embodied in different forms and should not be construedas limited to the embodiments set forth herein. Rather, theseembodiments are provided so that this disclosure will be thorough andcomplete, and will fully convey the scope of the invention to thoseskilled in the art.

The terminology used in the description of the invention herein is forthe purpose of describing particular embodiments only and is notintended to be limiting of the invention. As used in the description ofthe embodiments of the invention and the appended claims, the singularforms “a”, “an” and “the” are intended to include the plural forms aswell, unless the context clearly indicates otherwise. Also, as usedherein, “and/or” refers to and encompasses any and all possiblecombinations of one or more of the associated listed items.

The term “about,” as used herein when referring to a measurable valuesuch as an amount of a compound, dose, time, temperature, and the like,is meant to encompass variations of 20%, 10%, 5%, 1%, 0.5%, or even 0.1%of the specified amount. Unless otherwise defined, all terms, includingtechnical and scientific terms used in the description, have the samemeaning as commonly understood by one of ordinary skill in the art towhich this invention belongs.

As used herein, the terms “comprise,” “comprises,” “comprising,”“include,” “includes” and “including” specify the presence of statedfeatures, integers, steps, operations, elements, and/or components, butdo not preclude the presence or addition of one or more other features,integers, steps, operations, elements, components, and/or groupsthereof.

As used herein, the term “consists essentially of” (and grammaticalvariants thereof), as applied to the compositions and methods of thepresent invention, means that the compositions/methods may containadditional components so long as the additional components do notmaterially alter the composition/method. The term “materially alter,” asapplied to a composition/method, refers to an increase or decrease inthe effectiveness of the composition/method of at least about 20% ormore.

All patents, patent applications and publications referred to herein areincorporated by reference in their entirety. In case of a conflict interminology, the present specification is controlling.

Referring now to FIG. 1, a solid-state battery 10 comprising an anode12, a cathode 14 and a solid electrolyte 16 is provided in accordancewith one embodiment of the present invention. The solid-state batterymay further include an anode current collector 20 and a cathode currentcollector 22. A printable lithium composition is applied or deposited toa current collector, electrode and/or solid electrolyte of thesolid-state battery. For example, the printable lithium composition maybe used to form a monolithic lithium metal anode of various thicknessesand widths for use in a solid-state battery, including solid-statebatteries as described in U.S. Pat. Nos. 8,252,438 and 9,893,379 andincorporated herein by reference in their entireties. In yet anotherembodiment, the printable lithium composition may be applied ordeposited so as to form a solid electrolyte for a solid-state battery,and includes combining the ink composition with a polymer or ceramicmaterial to form a solid electrolyte. The printable lithium compositioncomprises a lithium metal powder, one or more polymer binders, one ormore rheology modifiers and may further include a solvent or co-solvent.

The printable lithium composition may be applied a current collector,electrode or solid electrolyte by various methods, including extruding,coating, printing, painting, dipping, and spraying as disclosed in U.S.application Ser. No. ______ (Attorney Matter ID 073396.1183, filedconcurrently with this application and hereby incorporated by referencein its entirety). For example, the anode may be lithiated orprelithiated by printing the printable lithium composition onto theanode or a current collector, where the thin lithium film withcontrolled thickness and width could be formed, or coating the anodewith the printable lithium composition.

In one embodiment, the printable lithium composition may be used toprelithiate a solid electrolyte as described in U.S. Pat. No. 7,914,930herein incorporated by reference in its entirety. One example of asolid-state secondary battery may include a positive electrode capableof electrochemically absorbing and desorbing lithium; a negativeelectrode capable of electrochemically absorbing and desorbing lithium,the negative electrode including an active material layer that comprisesan active material, the active material layer being carried on a currentcollector; and a non-aqueous electrolyte. A method includes the stepsof: reacting lithium with the active material of the negative electrodeby bringing the printable lithium composition into contact with asurface of the active material layer of the negative electrode; andthereafter combining the negative electrode with the positive electrodeto form an electrode assembly.

As disclosed in U.S. application Ser. No. ______ (Attorney Matter ID.073396.1116, filed concurrently with this application) and herebyincorporated by reference in its entirety, the printable lithiumcomposition comprises a lithium metal powder, a polymer binder, arheology modifier and may further include a solvent. The polymer bindermay be compatible with the lithium metal powder. The rheology modifiermay be compatible with the lithium metal powder and the polymer binder.The solvent may be compatible with the lithium metal powder and with thepolymer binder.

The lithium metal powder may be in the form of a finely divided powder.The lithium metal powder typically has a mean particle size of less thanabout 80 microns, often less than about 40 microns and sometimes lessthan about 20 microns. The lithium metal powder may be a lowpyrophoricity stabilized lithium metal power (SLMP®) available from FMCLithium Corp. The lithium metal powder may also include a substantiallycontinuous layer or coating of fluorine, wax, phosphorus or a polymer orthe combination thereof (as disclosed in U.S. Pat. Nos. 5,567,474,5,776,369, and 5,976,403). Lithium metal powder has a significantlyreduced reaction with moisture and air.

The lithium metal powder may also be alloyed with a metal. For example,the lithium metal powder may be alloyed with a Group I-VIII element.Suitable elements from Group IB may include, for example, copper,silver, or gold. Suitable elements from Group IIB may include, forexample, zinc, cadmium, or mercury. Suitable elements from Group IIA ofthe Periodic Table may include beryllium, magnesium, calcium, strontium,barium, and radium. Elements from Group IIIA that may be used in thepresent invention may include, for example, boron, aluminum, gallium,indium, or thallium. Elements from Group IVA that may be used in thepresent invention may include, for example, carbon, silicon, germanium,tin, or lead. Elements from Group VA that may be used in the presentinvention may include, for example, nitrogen, phosphorus, or bismuth.Suitable elements from Group VIIIB may include, for example, nickel,palladium, or platinum.

The polymer binder is selected so as to be compatible with the lithiummetal powder. “Compatible with” or “compatibility” is intended to conveythat the polymer binder does not violently react with the lithium metalpowder resulting in a safety hazard. The lithium metal powder and thepolymer binder may react to form a lithium-polymer complex, however,such complex should be stable at various temperatures. It is recognizedthat the amount (concentration) of lithium and polymer binder contributeto the stability and reactivity. The polymer binder may have a molecularweight of about 1,000 to about 8,000,000, and often has a molecularweight of 2,000,000 to 5,000,000. Suitable polymer binders may includeone or more of poly(ethylene oxide), polystyrene, polyisobutylene,natural rubbers, butadiene rubbers, styrene-butadiene rubber,polyisoprene rubbers, butyl rubbers, hydrogenated nitrile butadienerubbers, epichlorohydrin rubbers, acrylate rubbers, silicon rubbers,nitrile rubbers, polyacrylic acid, polyvinylidene chloride, polyvinylacetate, ethylene propylene diene termonomer, ethylene vinyl acetatecopolymer, ethylene-propylene copolymers, ethylene-propyleneterpolymers, polybutenes. The binder may also be a wax.

The rheology modifier is selected to be compatible with the lithiummetal powder and the polymer binder. The rheology modifier providesrheology properties such as viscosity. The rheology modifier may alsoprovide conductivity, improved capacity and/or improved stability/safetydepending on the selection of the rheology modifier. To this end, therheology modifier may be the combination of two or more compounds so asto provide different properties or to provide additive properties.Exemplary rheology modifiers may include one or more of carbon black,carbon nanotubes, graphene, silicon nanotubes, graphite, hard carbon andmixtures, fumed silica, titanium dioxide, zirconium dioxide and otherGroup IIA, IIIA, IVB, VB and VIA elements/compounds and mixtures orblends thereof.

Solvents compatible with lithium may include acyclic hydrocarbons,cyclic hydrocarbons, aromatic hydrocarbons, symmetrical ethers,unsymmetrical ethers, cyclic ethers, alkanes, sulfones, mineral oil, andmixtures, blends or cosolvents thereof. Examples of suitable acyclic andcyclic hydrocarbons include n-hexane, n-heptane, cyclohexane, and thelike. Examples of suitable aromatic hydrocarbons include toluene,ethylbenzene, xylene, isopropylbenzene (cumene), and the like. Examplesof suitable symmetrical, unsymmetrical and cyclic ethers includedi-n-butyl ether, methyl t-butyl ether, tetrahydrofuran, glymes and thelike. Commercially available isoparaffinic synthetic hydrocarbonsolvents with tailored boiling point ranges such as Shell Sol® (ShellChemicals) or Isopar® (Exxon) are also suitable.

The polymer binder and solvents are selected to be compatible with eachother and with the lithium metal powder. In general, the binder orsolvent should be non-reactive with the lithium metal powder or inamounts so that any reaction is kept to a minimum and violent reactionsare avoided. The binder and solvent should be compatible with each otherat the temperatures at which the printable lithium composition is madeand will be used. Preferably the solvent (or co-solvent) will havesufficient volatility to readily evaporate from the printable lithiumcomposition (e.g., in slurry form) to provide drying of the printablelithium composition (slurry) after application.

The components of the printable lithium composition may be mixedtogether as a slurry or paste to have a high concentration of solid.Thus the slurry/paste may be in the form of a concentrate with not allof the solvent necessarily added prior to the time of depositing orapplying. In one embodiment, the lithium metal powder should beuniformly suspended in the solvent so that when applied or deposited asubstantially uniform distribution of lithium metal powder is depositedor applied. Dry lithium powder may be dispersed such as by agitating orstirring vigorously to apply high sheer forces.

In another embodiment, a mixture of the polymer binder, rheologymodifier, coating reagents, and other potential additives for thelithium metal powder may be formed and introduced to contact the lithiumdroplets during the dispersion at a temperature above the lithiummelting point, or at a lower temperature after the lithium dispersionhas cooled such as described in U.S. Pat. No. 7,588,623 the disclosureof which is incorporated by reference in its entirety. The thuslymodified lithium metal may be introduced in a crystalline form or in asolution form in a solvent of choice. It is understood that combinationsof different process parameters could be used to achieve specificcoating and lithium powder characteristics for particular applications.

Conventional pre-lithiation surface treatments require compositionshaving very low binder content and very high lithium; for example, seeU.S. Pat. No. 9,649,688 the disclosure of which is incorporated byreference in its entirety. However, embodiments of the printable lithiumcomposition in accordance with the present invention can accommodatehigher binder ratios, including up to 20 percent on dry basis. Variousproperties of the printable lithium composition, such as viscosity andflow, may be modified by increasing the binder and modifier content upto 50% dry basis without loss of electrochemical activity of lithium.Increasing the binder content facilitates the loading of the printablelithium composition and the flow during printing. For example, in oneembodiment the printable lithium composition comprises about 70% lithiummetal powder and about 30% polymer binder and rheology modifiers. Inanother embodiment, the printable lithium composition may comprise about85% lithium metal powder and about 15% polymer binder and rheologymodifiers.

An important aspect of printable lithium compositions is the rheologicalstability of the suspension. Because lithium metal has a low density of0.534 g/cc, it is difficult to prevent lithium powder from separatingfrom solvent suspensions. By selection of lithium metal powder loading,polymer binder and conventional modifier types and amounts, viscosityand rheology may be tailored to create the stable suspension of theinvention. A preferred embodiment shows no separation at greater than 90days. This can be achieved by designing compositions with very high zeroshear viscosity in the range of 1×10⁴ cps to 1×10⁷ cps. It is howeververy important to the application process that the compositions, whenexposed to shear, exhibit viscosity characteristics in the rangesclaimed.

The resulting printable lithium composition preferably may have aviscosity at 10 s⁻¹ about 20 to about 20,000 cps, and often a viscosityof about 100 to about 10,000 cps. At such viscosity, the printablelithium composition is a flowable suspension or gel. The printablelithium composition preferably has an extended shelf life at roomtemperature and is stable against metallic lithium loss at temperaturesup to 60° C., often up to 120° C., and sometimes up to 180° C. Theprintable lithium composition may separate somewhat over time but can beplaced back into suspension by mild agitation and/or application ofheat.

In one embodiment, the printable lithium composition comprises on asolution basis about 5 to 50 percent lithium metal powder, about 0.1 to20 percent polymer binder, about 0.1 to 30 percent rheology modifier andabout 50 to 95 percent solvent. In one embodiment, the printable lithiumcomposition comprises on a solution basis about 15 to 25 percent lithiummetal powder, about 0.3 to 0.6 percent polymer binder having a molecularweight of 4,700,000, about 0.5 to 0.9 percent rheology modifier, andabout 75 to 85 percent solvent. Typically, the printable lithiumcomposition is applied or deposited to a thickness of about 50 micronsto 200 microns prior to pressing. After pressing, the thickness can bereduced to between about 1 to 50 microns. Examples of pressingtechniques are described, for example, in U.S. Pat. Nos. 3,721,113 and6,232,014 which are incorporated herein by reference in theirentireties.

In one embodiment, the printable lithium composition is deposited orapplied to an active anode material on a current collector namely toform a prelithiated anode. Suitable active anode materials includegraphite and other carbon-based materials, alloys such as tin/cobalt,tin/cobalt/carbon, silicon-carbon, variety of silicone/tin basedcomposite compounds, germanium-based composites, titanium basedcomposites, elemental silicon, and germanium. The anode materials may bea foil, mesh or foam. Application may be via spraying, extruding,coating, printing, painting, dipping, and spraying, and are described inco-pending US Patent Publication No. ______ (Attorney Matter073396.1183), filed concurrently herewith and incorporated herein byreference in its entirety.

In one embodiment, the active anode material and the printable lithiumcomposition are provided together and extruded onto the currentcollector (e.g., copper, nickel, etc.). For instance, the active anodematerial and printable lithium composition may be mixed and co-extrudedtogether. Examples of active anode materials include graphite,graphite-SiO, graphite-SnO, SiO, hard carbon and other lithium ionbattery and lithium ion capacitor anode materials. In anotherembodiment, the active anode material and the printable lithiumcomposition are co-extruded to form a layer of the printable lithiumcomposition on the current collector. The deposition of the printablelithium composition including the above extrusion technique may includedepositing as wide variety patterns (e.g., dots, stripes), thicknesses,widths, etc. For example, the printable lithium composition and activeanode material may be deposited as a series of stripes, such asdescribed in US Publication No. 2014/0186519 incorporated herein byreference in its entirety. The stripes would form a 3D structure thatwould account for expansion of the active anode material duringlithiation. For example, silicon may expand by 300 to 400 percent duringlithiation. Such swelling potentially adversely affects the anode andits performance. By depositing the printable lithium as a thin stripe inthe Y-plane as an alternating pattern between the silicon anode stripes,the silicon anode material can expand in the X-plane alleviatingelectrochemical grinding and loss of particle electrical contact. Thus,the printing method can provide a buffer for expansion. In anotherexample, where the printable lithium formulation is used to form theanode, it could be co-extruded in a layered fashion along with thecathode and separator, resulting in a solid-state battery.

In one embodiment, the printable lithium composition may be used topre-lithiate an anode as described in U.S. Pat. No. 9,837,659 hereinincorporated by reference in its entirety. For example, the methodincludes disposing a layer of printable lithium composition adjacent toa surface of a pre-fabricated/pre-formed anode. The pre-fabricatedelectrode comprises an electroactive material. In certain variations,the printable lithium composition may be applied to thecarrier/substrate via a deposition process. A carrier substrate on whichthe layer of printable lithium composition may be disposed may beselected from the group consisting of: polymer films (e.g., polystyrene,polyethylene, polyethyleneoxide, polyester, polypropylene,polypolytetrafluoroethylene), ceramic films, copper foil, nickel foil,or metal foams by way of non-limiting example. Heat may then be appliedto the printable lithium composition layer on the substrate or thepre-fabricated anode. The printable lithium composition layer on thesubstrate or the pre-fabricated anode may be further compressedtogether, under applied pressure. The heating, and optional appliedpressure, facilitates transfer of lithium onto the surface of thesubstrate or anode. In case of transfer to the pre-fabricated anode,pressure and heat can result in mechanical lithiation, especially wherethe pre-fabricated anode comprises graphite. In this manner, lithiumtransfers to the electrode and due to favorable thermodynamics isincorporated into the active material.

In additional embodiments, at least a portion of the printable lithiumcomposition can be supplied to the anode active material prior toassembly of the battery. In other words, the anode can comprisepartially lithium-loaded silicon-based active material, in which thepartially loaded active material has a selected degree of loading oflithium through intercalation/alloying or the like.

In one embodiment, the printable lithium composition may be incorporatedinto a three-dimensional electrode structure as described in USPublication No. 2018/0013126 herein incorporated by reference in itsentirety. For example, the printable lithium composition may beincorporated into a three-dimensional porous anode, porous currentcollector or porous polymer or ceramic film, wherein the printablelithium composition may be deposited therein.

In some embodiments, an electrode prelithiated with the printablelithium composition can be assembled into a cell with the electrode tobe preloaded with lithium. A separator can be placed between therespective electrodes. Current can be allowed to flow between theelectrodes. For example, an anode prelithiated with the printablelithium composition of the present invention may be formed into a secondbattery such as described in U.S. Pat. No. 6,706,447 herein incorporatedby reference in its entirety.

The cathode is formed of an active material, which is typically combinedwith a carbonaceous material and a binder polymer. The active materialused in the cathode is preferably a material that can be lithiated.Preferably, non-lithiated materials such as MnO₂, V₂O₅, MoS₂, metalfluorides or mixtures thereof, Sulphur and sulfur composites can be usedas the active material. However, lithiated materials such as LiMn₂O₄ andLiMO₂ wherein M is Ni, Co or Mn that can be further lithiated can alsobe used. The non-lithiated active materials are preferred because theygenerally have higher specific capacities, lower cost and broader choiceof cathode materials in this construction that can provide increasedenergy and power over conventional secondary batteries that includelithiated active materials.

EXAMPLES Example 1

10 g of solution styrene butadiene rubber (S-SBR Europrene Sol R 72613)is dissolved in 90 g toluene (99% anhydrous, Sigma Aldrich) by stirringat 21° C. for 12 hours. 6 g of the 10 wt % SBR (polymer binder) intoluene (solvent) is combined with 0.1 g carbon black (Timcal Super P)(rheology modifier) and 16 g of toluene and dispersed in a Thinky ARE250 planetary mixer for 6 minutes at 2000 rpm. 9.3 g of stabilizedlithium metal powder (SLMP®, Livent Corp.) having polymer coating of 20to 200 μm and d50 of 20 μm is added to this suspension and dispersed for3 minutes at 1000 rpm in a Thinky mixer. The printable lithium is thenfiltered through 180 μm opening stainless steel mesh. The printablelithium suspension is then doctor blade coated on to a copper currentcollector at a wet thickness of 2 mil (˜50 μm). FIG. 3 is a plot showingthe cycle performance for a pouch cell with printable lithium derivedthin lithium film as the anode vs. commercial thin lithium foil.

Example 2

10 g of 135,000 molecular weight ethylene propylene diene terpolymer(EPDM) (Dow Nordel IP 4725P) is dissolved in 90 g p-xylene (99%anhydrous, Sigma Aldrich) by stirring at 21° C. for 12 hours. 6 g of the10 wt % EPDM (polymer binder) in p-xylene (solvent) is combined with 0.1g TiO2 (Evonik Industries) (rheology modifier) and 16 g of toluene anddispersed in a Thinky ARE 250 planetary mixer for 6 minutes at 2000 rpm.9.3 g of stabilized lithium metal powder (SLMP®, Livent Corp.) havingpolymer coating of 20 to 200 μm and d50 of 20 μm is added to thissuspension and dispersed for 3 minutes at 1000 rpm in a Thinky mixer.The printable lithium is then filtered through 180 μm opening stainlesssteel mesh. The printable lithium composition is then doctor bladecoated on to a copper current collector at a wet thickness of 2 mil (˜50μm).

Shelf Life Stability

Printable lithium components must be selected to ensure chemicalstability for long shelf life at room temperature and stability atelevated temperature for shorter durations such as during transport orduring the drying process. The printable lithium composition stabilitywas tested using calorimetry. 1.5 g SLMP was added to a 10 ml volumeHastelloy ARC bomb sample container. 2.4 g of 4% SBR binder solution wasadded to the container. The container was fitted with a 24-ohmresistance heater and a thermocouple to monitor and control sampletemperature. The bomb sample set-up was loaded into a 350 ml containmentvessel along with insulation. An Advance Reactive Screening Systems Toolcalorimeter by Fauske Industries was used to assess the compatibility ofthe printable lithium solutions during a constant rate temperature rampto 190° C. The temperature ramp rate was 2° C./min and the sampletemperature was held at 190° C. for 60 minutes. The test was conductedunder 200 psi Argon pressure to prevent boiling of the solvent. FIG. 2shows the temperature and pressure profiles for the reactivity testingof a SLMP/styrene butadiene/toluene printable lithium composition.

Printing Performance

The quality of the printable lithium composition with regard toprintability is measured by several factors, for example, consistency offlow which directly impact one's ability to control lithium loading on asubstrate or an electrode surface. An effective means of measuring flowis Flow Conductance which is an expression of the loading per squarecentimeter in relation to the factors which control the loading—thepressure during extrusion and the speed of the printer head. It can mostsimply be thought of as the inverse of flow resistance.

The expression is used to allow comparisons between prints of varyingpressures and speeds, and changes in Flow Conductance can alert one tonon-linear relationships of flow with pressure. These are important forscaling the loading for a printable lithium up or down depending on theneed of the anode or cathode. An ideal printable lithium compositionwould behave in a linear fashion to changes in extrusion pressure.

To test printability, a printable lithium composition is filteredthrough 180 μm opening stainless steel mesh and loaded into a NordsonEFD 10 ml syringe. The syringe is loaded into a Nordson EFD HP4x syringedispenser and attached to a slot die print head. The slot die print headis equipped with a 100 μm-300 μm thick shim with channel openingsdesigned to deliver the desired printable lithium composition loading.The slot die head is mounted on a Loctite 300 Series robot. The printhead speed is set to 200 mm/s and the printing pressure is between 20and 200 psi argon, depending on shim and channel design. The printlength is 14 cm. In an example printing trial experiment, the printablelithium composition was printed 30 times from a single syringe atdispenser settings ranging from 80 psi to 200 psi. For this print trialexperiment, the flow conductance average was

$0.14\frac{mg}{s*{cm}^{2}}*\frac{lbf}{{in}^{2}}$

with standard deviation of 0.02. Although this printable compositiondoes not behave in a perfectly linear fashion, the composition flowresponse to changes in dispenser pressure is predictable to allow oneskilled in the art to fine tune lithium loading to the desired level.Thus, at fixed dispenser pressure conditions the loading of lithium canbe controlled very consistently. For example, for a print of

$0.275\frac{mAh}{{cm}^{2}}$

lithium metal, the CV is about 5%.

Electrochemical Testing

The pre-lithiation effect of printable lithium composition can beevaluated by printing the required amount of printable lithium onto thesurface of prefabricated electrodes. The pre-lithiation lithium amountis determined by testing the anode material in half-cell format andcalculating the lithium required to compensate for the first cyclelosses due to formation of SEI, or other side reactions. To calculatethe necessary amount of printable lithium, the capacity as lithium metalof the composition must be known and is approximately 3600 mAh/g drylithium basis for the compositions used as examples.

The pre-lithiation effect is tested using Graphite-SiO/NCA pouch cells.The Graphite-SiO anode sheet has the following formulation: artificialgraphite (90.06%)+SiO (4.74%)+carbon black (1.4%)+SBR/CMC (3.8%). Thecapacity loading of the electrode is 3.59 mAh/cm² with 87% first cycleCE (columbic efficiency). The printable lithium is applied onto aGraphite-SiO anode at 0.15 mg/cm² lithium metal. The electrode is driedat 80° C. for 100 min followed by lamination at a roller gapapproximately 75% of the thickness of the electrode. A 7 cm×7 cmelectrode is punched from the printable lithium treated anode sheet. Thepositive electrode has the following formulation: NCA (96%)+carbon black(2%)+PVdF (2%). The positive electrode is 6.8 cm×6.8 cm with capacityloading of 3.37 mAh/cm². The NCA cathode has 90% first cycle CE. Theanode to cathode capacity ratio is 1.06 and the baseline for full cellfirst cycle CE is 77%. Single layer pouch cells are assembled and 1MLiPF₆/EC+DEC (1:1) is used as the electrolyte. The cells arepre-conditioned for 12 hours at 21° C. and then the formation cycle isconducted at 40° C. The formation protocol is 0.1 C charge to 4.2V,constant voltage to 0.01 C and 0.1 C discharge to 2.8V. In the describedtest 89% first cycle CE was demonstrated.

Although the present approach has been illustrated and described hereinwith reference to preferred embodiments and specific examples thereof,it will be readily apparent to those of ordinary skill in the art thatother embodiments and examples may perform similar functions and/orachieve like results. All such equivalent embodiments and examples arewithin the spirit and scope of the present approach.

That which is claimed is:
 1. A solid-state battery comprising a cathode,an anode and a solid electrolyte, wherein at least the anode, cathodeand/or solid electrolyte is formed from a printable lithium compositioncomprised of lithium metal powder, a polymer binder compatible with thelithium metal powder, a rheology modifier compatible with the lithiummetal powder, and a solvent compatible with the lithium metal powder andwith the polymer binder.
 2. The solid-state battery of claim 1, whereinthe anode and/or cathode is formed by printing the printable lithiumcomposition onto the anode and/or cathode.
 3. The solid-state battery ofclaim 1, wherein the anode is formed by printing the printable lithiumcomposition onto a current collector.
 4. The solid-state battery ofclaim 1, wherein the anode and/or cathode is formed by coating the anodewith the printable lithium composition.
 5. The solid-state battery ofclaim 1, wherein the anode and/or cathode is formed by depositing theprintable lithium composition onto the anode using an electric current.6. The solid-state battery of claim 1, wherein the lithium powder isstabilized lithium metal powder.
 7. The solid-state battery of claim 1,wherein the rheology modifier is selected from the group consisting ofcarbonaceous materials, silicon-containing materials, tin-containingmaterials, Group IIA oxides, Group IIIA oxides, Group IVB oxides, GroupVB oxides and Group VIA oxides.
 8. The solid-state battery of claim 7,wherein the carbonaceous material is selected from the group consistingof carbon black, carbon nanotubes, graphite, hard carbon, and graphene.9. The solid-state battery of claim 7, wherein the silicon-containingmaterial is selected from the group consisting of silicon nanotubes andfumed silica.
 10. The solid-state battery of claim 7, wherein the GroupIVB oxide is selected from the group consisting of titanium dioxide andzirconium dioxide.
 11. The solid-state battery of claim 7, wherein theGroup IIIA oxide is aluminum oxide.
 12. The solid-state battery of claim1, wherein the polymer binder has a molecular weight of 1,000 to8,000,000 and is selected from the group consisting of unsaturatedelastomers, saturated elastomers, thermoplastics, polyacrylic acid,polyvinylidene chloride, and polyvinyl acetate.
 13. The solid-statebattery of claim 12, wherein the unsaturated elastomer is selected fromthe group consisting of butadiene rubber, isobutylene, and styrenebutadiene rubber.
 14. The solid-state battery of claim 12, wherein thesaturated elastomer is selected from the group consisting of ethylenepropylene diene monomer rubber and ethylene-vinyl acetate.
 15. Thesolid-state battery of claim 12, wherein the thermoplastic is selectedfrom the group consisting of polystyrene, polyethylene and polymers ofethylene oxide.
 16. The solid-state battery of claim 15, wherein thepolymers of ethylene oxide is selected from the group consisting ofpoly(ethylene glycol) and poly(ethylene oxide).
 17. The solid-statebattery of claim 1, wherein the solvent is selected from the groupconsisting of alkanes, toluene, ethylbenzene, cumene, xylene, sulfones,mineral oil, glymes, and isoparaffinic synthetic hydrocarbon solvents.18. The solid-state battery of claim 1, wherein the printable lithiumcomposition comprises on a solution basis: a) 5 to 50 percent lithiummetal powder; b) 0.1 to 20 percent polymer binder; c) 0.1 to 30 percentrheology modifier; d) 50 to 95 percent solvent.
 19. The solid-statebattery of claim 1, wherein the lithium is deposited onto the solidelectrolyte using the printable lithium composition.
 20. A solid-statebattery comprising a cathode, an anode and a solid electrolyte, whereinlithium is deposited onto the solid electrolyte with a lithium printablelithium composition comprised of lithium metal powder, a polymer bindercompatible with the lithium metal powder, a rheology modifier compatiblewith the lithium metal powder and the polymer binder, and a solventcompatible with the lithium metal powder and with the polymer binder.21. The solid-state battery of claim 20, wherein lithium is depositedonto the solid electrolyte by printing the printable lithium compositiononto the solid electrolyte.
 22. The solid-state battery of claim 20,wherein lithium is deposited onto the solid electrolyte by coating thesolid electrolyte with the printable lithium composition.
 23. Thesolid-state battery of claim 20, wherein the lithium powder isstabilized lithium metal powder.
 24. The solid-state battery of claim20, wherein the rheology modifier is selected from the group consistingof carbonaceous materials, silicon-containing materials, tin-containingmaterials, Group IIA oxides, Group IIIA oxides, Group IVB oxides, GroupVB oxides and Group VIA oxides.
 25. The solid-state battery of claim 24,wherein the carbonaceous material is selected from the group consistingof carbon black, carbon nanotubes, graphite, hard carbon, and graphene.26. The solid-state battery of claim 24, wherein the silicon-containingmaterial is selected from the group consisting of silicon nanotubes andfumed silica.
 27. The solid-state battery of claim 24, wherein the GroupIVB oxide is selected from the group consisting of titanium dioxide andzirconium dioxide.
 28. The solid-state battery of claim 24, wherein theGroup IIIA oxide is aluminum oxide.
 29. The solid-state battery of claim20, wherein the polymer binder has a molecular weight of 1,000 to8,000,000 and is selected from the group consisting of unsaturatedelastomers, saturated elastomers, thermoplastics, polyacrylic acid,polyvinylidene chloride, and polyvinyl acetate.
 30. The solid-statebattery of claim 29, wherein the unsaturated elastomer is selected fromthe group consisting of butadiene rubber, isobutylene, and styrenebutadiene rubber.
 31. The solid-state battery of claim 29, wherein thesaturated elastomer is selected from the group consisting of ethylenepropylene diene monomer rubber and ethylene-vinyl acetate.
 32. Thesolid-state battery of claim 29, wherein the thermoplastic is selectedfrom the group consisting of polystyrene, polyethylene and polymers ofethylene oxide.
 33. The solid-state battery of claim 32, wherein thepolymers of ethylene oxide is selected from the group consisting ofpoly(ethylene glycol) and poly(ethylene oxide).
 34. The solid-statebattery of claim 20, wherein the solvent is selected from the groupconsisting of alkanes, toluene, ethylbenzene, cumene, xylene, sulfones,mineral oil, glymes, and isoparaffinic synthetic hydrocarbon solvents.35. The solid-state battery of claim 20, wherein the printable lithiumcomposition comprises on a solution basis: a) 5 to 50 percent lithiummetal powder; b) 0.1 to 20 percent polymer binder; c) 0.1 to 30 percentrheology modifier; d) 50 to 95 percent solvent.
 36. The solid-statebattery of claim 20, wherein the anode is lithiated using the printablelithium composition.